Download air pressure and wind

Air Pressure and Wind
By Sharon Fabian
Air is the atmosphere that is always around us. Most of the time we don't even
notice that it is there. We are so used to living in this ocean of air that we don't even
feel it most of the time. But when the air moves, that's a different story. We can feel
the change when the wind blows and when the air pressure drops or rises. Air
pressure and wind are two features of wind that are very noticeable.
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Air pressure is the weight of the air pressing down on us and on everything else around us. It is what
makes a balloon get bigger when you blow it up. Air pressure also causes the air to shoot out all at once
when you poke even a tiny hole in a balloon. Air pressure is what makes your ears pop when you go up a
mountain. This happens because the air pressure inside your body and the air pressure outside are usually
balanced, but when you go up a mountain the pressures become unbalanced. There is less pressure in the
air on top of a mountain than there is at lower altitudes. So your ears pop to let the pressures even out.
Baseball pitchers even make use of air pressure when they throw a curveball. It helps to cause the
spinning motion that makes the ball curve.
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Weather forecasters use air pressure everyday in their job. They use a measuring instrument called a
barometer to measure air pressure, which helps them to predict whether the day will be clear, rainy, or
stormy. When the barometer shows that the air pressure is high, they can predict cool, clear weather.
When the air pressure is low, they expect warmer weather, and may predict rain or storms.
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You can make a simple barometer to see how air pressure is measured for yourself. You will need a
glass bottle about half full of water, a clear plastic straw that you put in the bottle, and a stopper to close
up the rest of the top of the bottle. As the air pressure changes, the water in the straw should move up or
down.
4
Wind is moving air. Since you can't see air, you also can't see wind directly, but you can observe wind
by watching the movements or listening to the sounds that the moving air produces. Wind causes a flag to
wave and a sailboat to sail. It causes wind chimes to chime.
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Air pressure and wind combine to cause some very dramatic events. Tornadoes, hurricanes, and
thunderstorms are all powered by air pressure and wind.
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A hurricane for example, usually forms out over the ocean when a large area of the ocean water becomes
warmer than usual. The heat causes the air pressure there to drop, and this causes both thunderstorms and
strong winds to develop. This is the beginning of a hurricane. Strong, spiraling winds cause the hurricane
to move and pick up more energy along the way. An area of high pressure called the Bermuda High often
directs hurricanes towards the United States.
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Even though we can't see or feel air, we know that it is there. We can observe its effects in the forces of
air pressure and wind.
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Copyright © 2013 edHelper
Name _____________________________
Science Pd ___________________
Air Pressure and Wind
1. Moving air is called _____.
Air pressure
Barometer
Air
Wind
3. An instrument for measuring air pressure
is a _____.
Scale
Thermometer
Meter stick
Barometer
5. _____ causes wind chimes to chime.
Wind
Air pressure
7. Which of the following is true about
observing air?
We cannot always see or feel air.
We can observe air through the
actions of air pressure and wind.
We cannot observe air.
Both a and b
2. The force of the air pressing down on us
is called _____.
Air pressure
Wind
Barometer
Air
4. We usually don't notice air pressure
because _____.
Air pressure only happens in stormy
weather
There usually isn't much air pressure
The air pressure inside and outside
our body is usually balanced
We only notice it when the wind
blows
6. _____ causes your ears to pop when you
go up a mountain.
Wind
Air pressure
8. Think of a weather forecast that you have
watched on TV. What is one thing that the
forecaster might have said that told you
that he had been observing air pressure or
wind in preparing his forecast?